Process for dechlorinating water



Patented May 12, 1931 rattan ERNST BERL, OF DARMSTADT, GERMANY PROCESS FOR DECHLORINA'IING WATER Ito Drawing. applicatioh filed October 10, 1929, Serial No. 398,804, and in Germany May 10, 1926.

lmpure waters are frequently treated with chlorine for example liquid chlorine or perchloride' compounds, an excess of chlorine being generally used in order to destroy any infectious germs which are present.

The present invention relates to the dechlorination of such water.

It is well known that the chlorine excess can be removed by means of salts. as for ex- U ample, sodium thio-sulphate. The water then, however, has a disagreeable salty taste. Endeavour-s have also been made to remove the chlorine by means of active carbon and the like. This rocess, however, is expensive as it only ena les the dechlorina-tion to be efi'ected eiiiciently by the use of comparatively large quantities of active carbon,

whilst finely divided particles of carbon pass 05 with the treated water and impart thereto a grey colouration. 4 c

It is also known to filter chlorinated water through substances such as peat, brown coal and the like. The use of such raw products is however liable to render the water impure.

According to the present invention the dechlorination of the water is effected by the treatment thereof with lignin. If the water is brought into intimate contact with lignin the chlorine contained therein combines completely with'the lignin whilst forming tasteless and odourless lignin chloride.

Water which contains only small quantities of chlorine in excess may be used directly after treatment with lignin even also foredible purposes as the small quantities of ligninchloride contained therein do not have a disturbing efiect.

It is however possible to readily remove the lignin chloride from the water for example in such a manner that it is filteredthrough carbon of difi'erent types as for example brown coal coke, brown coal, coal and so forth from which disturbing substances as for example ulrnic substances, bitumen and the like have been removed by theusual methods of extraction for instance with tetrahydronaphthalene, benzol, acetone S0 or for example in such a manner that the water containing lignin chloride is treated been obtained from substances containing lignin. When decomposing initial substances containing cellulose and lignin, such as wood, by means of concentrated acid, particularly hydrochloric acid, the cellulose for example is converted into a form soluble in acid or exhaust products (types of sugar) whilst thelignin remains as residue; Such lignin, after purification, for example by washing, and after sterilization if desired, can be used in connection with a process of the present application.

Instead of lignin it is also possible to use substances containing lignin which do not impart disturbing impurities to the water. As such may be mentioned for example wood waste, such as saw-dust, wood-fiour and the like.

The treatment of chlorinated water with lignin, saw-dust and the like may for example be carried out in such a manner that the water is filteredthrough the lignin or the lignin-containing substances or by bringing the water into mtimate contact with solid substances by other suitable operations as for example vibratingmethods.

Enema/plea l. Stron chlorinated water or chlorine water, the atter with a content of morecthan 3 grammes er litre, therefore, more than 3,000 times t 1e quantit which is used for the dechlorination of drin ing water, (less than 1 gramme chlorine per cubic metre of water) 5 is filtered through lignin free from germs, produced according to Willstiitter, or shaken therewith. With every grammes of lignin it is possible to remove at least 5 grammes of ch orine so completely that examination of the water by known means will no longer enable an content of chlorine to be recognized. A ter filtration through active carbon or bleaching earth an entirely clear water having an excellent taste is obtained and which is free from any infectious erms.

2. Chlorinated water or example 0.6 grammes chlorine per cubic metre is filtered through wood (for example sawust, which is preferably free from resin, steamed and thus rendered free from germs), or shaken therewith. After a short time the water has been completely dechlorinated. If the initial water had a small content of chlorine it is capable of bein used for edible purposes without any furt or subsequent treatment.

I claim 1. A water purifying process which comprises treating the water with chlorine or perchloride compounds, treating the chlorinated water with a lignin bearing material to convert the chlorine into lignin chloride and substantially continuously maintaining throughout the treatment the ratio between the lignin and the chlorine at a proportion 36 of substantially 2 to 1 parts by weight or above.

2. A process according to claim 1, in which the water is treated with lignin-containing substances which do not impart impurities to 40 the water.

3. A process according to claim 1, in which the water is treated with substances which contain lignin in combination with cellulose.

4. A process accordin to claim 1, in which the water is treated with colnminuted wood.

5. A process for the removal-of chlorine or perch oride compounds from Water treated therewith, consistin in treating the water to be dechlorinated wit lignin and then with substances which are capable of removing the lignin chloride which has been formed.

6. A process for the removal of chlorine or perchloride compounds from water treated therewith, consisting in treating the water (with lignin and then treating it with substances which are capable of combining with the lignin chloride.

7. A process for the removal of chlorine or perchloride compounds from water treated therewith, consisting in treating the water to be dechlorinated with lignin and then treating it with carbon from which ulmic substances and bitumen have been removed.

8. A process for the removal of chlorine or perchloride compounds from water treated therewith, consisting in treating the water to be dechlorinated with lignin and then treating it with adsorption media.

9. A process for the removal of chlorine or perchloride compounds from water treated therewith, consistin in treating the water to be dechlorinated wit lignin, then treating it with carbon from which ulmic substances and bitumen have been removed and finally treating it with active adsorption media.

In testimony whereof I aifix my signature.

' ERNST BERL. 

